1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Copyright (c) Wipro Technologies Ltd, 2002. All Rights Reserved.
3 * Author: Vatsal Avasthi
4 *
5 * Test Description:
6 * This test verifies that flock() behavior with different locking
7 * combinations along with LOCK_SH and LOCK_EX:
8 * 1) flock() succeeded in acquiring shared lock on shared lock file.
9 * 2) flock() failed to acquire exclusive lock on shared lock file.
10 * 3) flock() failed to acquire shared lock on exclusive lock file.
11 * 4) flock() failed to acquire exclusive lock on exclusive lock file.
12 */
13
14 #include <errno.h>
15 #include <sys/file.h>
16 #include <stdlib.h>
17
18 #include "tst_test.h"
19
20 static struct tcase {
21 int operation;
22 char *f_lock;
23 } tcases[] = {
24 {LOCK_SH, "shared lock"},
25 {LOCK_EX, "exclusive lock"},
26 };
27
child(int opt,int should_pass,char * lock)28 static void child(int opt, int should_pass, char *lock)
29 {
30 int retval, fd1;
31
32 fd1 = SAFE_OPEN("testfile", O_RDWR);
33 retval = flock(fd1, opt);
34 if (should_pass) {
35 tst_res(retval == -1 ? TFAIL : TPASS,
36 " Child acquiring %s got %d", lock, retval);
37 } else {
38 tst_res(retval == -1 ? TPASS : TFAIL,
39 " Child acquiring %s got %d", lock, retval);
40 }
41
42 SAFE_CLOSE(fd1);
43 exit(0);
44 }
45
verify_flock(unsigned n)46 static void verify_flock(unsigned n)
47 {
48 int fd2;
49 pid_t pid;
50 struct tcase *tc = &tcases[n];
51
52 fd2 = SAFE_OPEN("testfile", O_RDWR);
53 TEST(flock(fd2, tc->operation));
54 if (TST_RET != 0) {
55 tst_res(TFAIL | TERRNO, "flock() failed to acquire %s",
56 tc->f_lock);
57 SAFE_CLOSE(fd2);
58 return;
59 }
60
61 tst_res(TPASS, "Parent had %s", tc->f_lock);
62
63 pid = SAFE_FORK();
64 if (pid == 0)
65 child(LOCK_SH | LOCK_NB, tc->operation & LOCK_SH, "shared lock");
66 else
67 tst_reap_children();
68
69 pid = SAFE_FORK();
70 if (pid == 0)
71 child(LOCK_EX | LOCK_NB, 0, "exclusive lock");
72 else
73 tst_reap_children();
74
75 SAFE_CLOSE(fd2);
76 }
77
setup(void)78 static void setup(void)
79 {
80 int fd;
81
82 fd = SAFE_OPEN("testfile", O_CREAT | O_TRUNC | O_RDWR, 0644);
83 SAFE_CLOSE(fd);
84 }
85
86 static struct tst_test test = {
87 .tcnt = ARRAY_SIZE(tcases),
88 .test = verify_flock,
89 .needs_tmpdir = 1,
90 .setup = setup,
91 .forks_child = 1,
92 };
93